Replace size reporting with sysfs helper; keep fdisk for partition tables

fdisk -l can’t be trusted inside Heads’ initrd: busybox limits it to
2 TiB and parsing its output is fragile.

Changes relative to origin/master:

  * add new function disk_info_sysfs() in initrd/etc/functions
    – walks /sys/block, skips partition entries, and computes a byte
      count (preferring blockdev --getsize64, otherwise size*512)
    – converts to decimal GB, switching to TB for ≥1000 GB
  * update show_system_info() (gui_functions & oem‑system‑info‑xx30) to call the
    helper and no longer invoke `fdisk -l` for size output
  * add TRACE_FUNC/DEBUG logging around the helper invocation

Tested in qemu/debian‑13/PureOS; only the size line differs, other behaviour
is identical to master.

Signed-off-by: Thierry Laurion <insurgo@riseup.net>

Author: tlaurion

initrd/etc/functions

@@ -1297,36 +1297,12 @@ verify_checksums() {
 # Check if a device is an LVM2 PV, and if so print the VG name
 find_lvm_vg_name() {
 	TRACE_FUNC
-	local DEVICE VG part
+	local DEVICE VG
 	DEVICE="$1"
 
-	# closing fd10 should be handled by callers (detect_root_device now
-	# closes it for commands before invoking us).  leaving this here can
-	# interfere with future uses of fd10 elsewhere in the same shell.
-	# (Note: previous versions contained a hack to close it here; see
-	# commit 700ed0c141.)
-
 	mkdir -p /tmp/root-hashes-gui
-	# Try to query whether DEVICE is an LVM physical volume.  On systems
-	# without LVM the command may not exist; treat that like "not a PV".
-	if ! lvm pvs --noheadings -o vg_name "$DEVICE" >/tmp/root-hashes-gui/lvm_vg 2>/tmp/root-hashes-gui/lvm_err; then
-		# It's not an LVM PV, or lvm failed entirely.  Log stderr for debugging.
-		DEBUG "lvm pvs failed for $DEVICE, stderr:" "$(cat /tmp/root-hashes-gui/lvm_err)"
-		# try any children shown by lsblk (handles LUKS containers with
-		# internal partitions such as dm-0, dm-1 etc).
-		if command -v lsblk >/dev/null 2>&1; then
-			DEBUG "find_lvm_vg_name: lsblk children of $DEVICE"
-		DO_WITH_DEBUG lsblk -np -l -o NAME "$DEVICE" 2>/dev/null | tail -n +2
-			for part in $(lsblk -np -l -o NAME "$DEVICE" | tail -n +2); do
-				[ -b "$part" ] || continue
-				DEBUG "find_lvm_vg_name: testing child $part"
-				if lvm pvs --noheadings -o vg_name "$part" >/tmp/root-hashes-gui/lvm_vg 2>/tmp/root-hashes-gui/lvm_err; then
-					VG="$(awk 'NF {print $1; exit}' /tmp/root-hashes-gui/lvm_vg)"
-					[ -n "$VG" ] && { echo "$VG"; return 0; }
-				fi
-			done
-		fi
-		DEBUG "find_lvm_vg_name: $DEVICE is not an LVM PV"
+	if ! lvm pvs --noheadings -o vg_name "$DEVICE" >/tmp/root-hashes-gui/lvm_vg 2>/dev/null; then
+		# It's not an LVM PV
 		return 1
 	fi